1. Field of the Invention
The present invention relates to dies having an identification (e.g. security feature, logo) for the production of a coating (decorative finish) which can be bonded to a sheet-like substrate, in particular a leather or a textile material, such as a nonwoven, woven fabric or knitted fabric, or a wood surface, and which is formed by application of a liquid plastic material to the surface of the die and subsequent solidification of the plastic material, the identification being transferred to the coating. The invention furthermore relates to a process for the production of the dies by means of laser engraving. The invention furthermore relates to laser-engraved dies having the identification, which are obtainable by the process.
2. Description of Related Art
In the direct laser engraving technique, a three-dimensional structure is engraved directly into a material surface. This technique has attracted broader economic interest only in recent years with the appearance of improved laser systems. The improvements in the laser systems include better focusability of the laser beam, higher power and computer-controlled beam guidance.
Direct laser engraving has a plurality of advantages over conventional, for example mechanical, structuring processes. For example, three-dimensional motif elements can be individually formed in the laser engraving technique. Certain elements can be produced so as to be different from other elements, for example with regard to depth and steepness. Furthermore, in principle any digital original motif can be engraved into a material surface by means of the laser engraving technique after suitable conversion into a three-dimensional relief image, whereas, in conventional structuring techniques, the three-dimensional shape of elements is limited whether by a natural three-dimensional original or the geometry of the imaging tool. Finally, the laser engraving process is highly automatable so that the entire process is not very susceptible to individual errors and is very readily reproducible. In this way, structured materials can be produced in high constant quality.
EP-A 0 640 043 and EP-A 0 640 044 disclose, respectively, one-layer and multi-layer elastomeric laser-engravable recording elements for the production of flexographic printing plates. The elements consist of reinforced elastomeric layers. For the production of the layer, elastomeric binders, in particular thermoplastic elastomers, such as SBS, SIS or SEBS block copolymers, are used. As a result of the so-called reinforcement, the mechanical strength of the layer is increased in order to permit flexographic printing. The reinforcement is achieved either by introducing suitable fillers, photochemical or thermochemical crosslinking or combinations thereof.
WO 2005/047549 describes a process for the production of a finish for leather, in which the finish is produced on a silicone rubber substrate, the substrate having a structured surface corresponding to the grain structure of the finish. Furthermore, the process for the production of a substrate provided on its visible side with a finish having a grain structure, in particular a grain leather, a split leather having a buffed top or a synthetic suede material having a top consisting of microfibers, is disclosed, first, for the formation of the finish, an aqueous plastic dispersion being applied to a substrate consisting of a silicone rubber and having a structured surface corresponding to the grain structure of the finish and being left to solidify to form a film.
Product piracy has become a serious problem for the economy. Modern production techniques and the worldwide exchange of goods make it easy today to produce virtually identical copies of profitable products and introduce them into lucrative domestic and foreign markets. Inter alia, the products of the leather, textile, shoe and apparel industry and the furniture industry are affected. It is therefore desirable to provide the surface-structured decorative finishes with a security identification which can be copied only with difficulty.